Flip-chip attachment of large thin dies with TSVs for 3D applications often results in warpage control issues when a mass reflow process is used. Bottom die warpage can prevent top die attachment when micropillars are used as the interconnect since a near flat surface is required on the backside of the bottom die. Warpage is more severe with higher numbers of back-end-of-line (BEOL) layers.
A need therefore exists for methodology enabling warpage control on the backside of a thinned TSV die and the resulting device.